Question #2776

A digital clock has a resistance of 1.00 x 10^4 W and is plugged into a 110.0-V outlet. If the owner pays $0.05 per kWh, how much does it cost to operate the clock for 30.0 days?

Expert's answer

The power dissipated by a linear resistor may be calculated from its resistance, and voltage or current. The formula is a combination of Ohm's law and Joule's laws:

P = V^{2}/R = 110^{2}/10^{4} = 12100/10000 = 12.1 W.

Working 30 days we will have

P_{tot} = 12.1*30*24 = 8712.

Finally we get

$ = 8712*0.05 = 435.6.

P = V

Working 30 days we will have

P

Finally we get

$ = 8712*0.05 = 435.6.

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